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In this photo taken May, 29, 2010 in Savoy, Ill., month-old corn grows in a field. A minuscule pest has made its way from corn-belt states in the U.S. and is now slowly chewing its was through crops in Canada. (David Mercer/Davider Mercer/ The Canadian Press)
In this photo taken May, 29, 2010 in Savoy, Ill., month-old corn grows in a field. A minuscule pest has made its way from corn-belt states in the U.S. and is now slowly chewing its was through crops in Canada. (David Mercer/Davider Mercer/ The Canadian Press)

Tiny American pest puts the bite on Canadian corn Add to ...

A minuscule pest has made its way from corn belt states in the U.S. and is slowly chewing its way through crops in Canada.

Entomologists aren't sure why the western bean cutworm began migrating, but can confirm the critter has popped up in Ontario and Quebec cornfields.

"This is the first year we're anticipating a significant problem," said Art Schaafsma, an expert in field crop pest management with Guelph University.

In just one year, there's been a proliferation not only in the insect's numbers, but also in the number of regions where it's been found. "We've been getting significant trap catches," Prof. Schaafsma said. "Last year it was more of a token catch."

Newly hatched larvae are a dull tan or pink colour with black heads. They feed on the plant's pollen, its silk and, later, on its developing kernels. Its feeding can open up the ear to other pests, diseases and fungal infections.

Farmers in Ontario and Quebec are being asked to scout for egg masses - pearly thumb-tip-sized patches of eggs that turn purple before hatching - and for the larvae.

Prof. Schaafsma said the worst infestation he's seen so far was in one Ontario field. Eggs were found on 25 per cent of plants, an invasion he estimates could cost the farmer 10 to 15 per cent of his crop yield. "It hits the farmer in the pocketbook," he said.

Still, he says farmers shouldn't panic, cautioning that Canada's bug problem is mild compared with the cutworm invasion in some U.S. states.

Claude Parent, an agronomist with the Quebec Ministry of Agriculture, agrees the contamination is - for now - on a relatively small scale. "We'll see some damage in a couple of fields," he said. "But if we look at how it spread elsewhere, it starts small. In all the [U.S.]states we saw the population slowly increase."

The bugs moved into Ontario in 2008 and spread to Quebec a year later. The pretty adult moth, with its star- and crescent-moon wing markings, had flown northeast from Nebraska, Arkansas and Colorado.

The migration was first reported in Michigan a few years ago, and farmers in the border state are now reporting significant damage to their crops.

The insect also dines on dry beans - though not soybeans - and to a lesser extent on tomatoes and nightshade.

In Canada, large numbers of the eggs have been found in fields around Bothwell and Strathroy in Southern Ontario, and near Lorrainville and Shawville in Quebec, near the Ontario line.

At the moment, dry bean crops in the country are free from the cutworm, which seems more attracted to Canadian corn. For this, Mr. Parent breathes a sigh of relief. Dry beans - like kidney, pinto and romano beans - are extremely vulnerable to the pest.

Corn farmers have two weapons in the battle against the cutworm: spraying with insecticides, or planting a breed of transgenic corn modified to produce a specific insecticidal protein.

Entomologists are still studying the most effective way to spray the tough-to-kill pests, which can be hard to reach with chemicals once they've moved down into the ear of the corn.

"We don't like to be spraying willy-nilly," Prof. Schaafsma said.

They are also still trying to unlock why the insect suddenly started to settle in Canada. They do know it seems to prefer sandy soil into which it can burrow and survive the winter. "It has adapted to something that has changed," he said. "We're not entirely sure what."

He said higher temperature due to climate change is only one possible theory among many. The insect's behaviour could also be linked to shifts in farming practices such as a move to a specific type of corn, changes in crop rotation, or even a sudden adaptation of the insect itself.

"Right now it's a puzzle," he said. "It's challenging to say the least."

The Canadian Press

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